Welcome to the Community - So I understand the questions you are looking to keep on VM on a certain host and then make sure other VMs do not vmotion to that host - if this is the case than what you will have to do is this:
On the VM you do not want to move you will need to set a custom automation level for that VM to DIsable - for the vms you do not want to move to the host you will need to configure Anti-Affinity rules - check out section 9 and 10 in http://pubs.vmware.com/vsphere-51/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-51-resource-management-guide.pdf